发现语言指令会泄漏到模型预测中,导致看似懂空间关系实则只是抄指令。
Grounding Spatial Relations in a Compact World Model: Instruction Leakage and a Goal-Free Dynamics Fix

- 用指令名称直接预测目标位置,而非真正感知场景。
- 去除指令后准确率从90%暴跌至27%,说明依赖指令而非视觉输入。
- 提出新训练方式:让模型读取世界状态,而非受指令干扰,恢复真实理解能力。
紧凑的世界模型通过语言目标条件化,试图用少量参考锚点来理解如“将红块放在蓝块左侧”这类空间关系。我们发现,看似高精度的0.90关系识别实际上只是指令转录,而非真实感知。当隐藏目标指令时,准确率骤降至0.27(三组种子),而使用反事实指令时,模型仍以94.5%概率预测错误位置(真实场景仅2.3%),表明存在指令泄漏。这一现象在三个设置及任务内消融中均成立。核心结论是:当评分量可直接从指令中推断出(如指令命名答案)时,便出现指令泄漏,且与非指令输入的预测能力无关。桌面任务和BabyAI基准存在此问题,而语言-表前向动力学模型若不命名方向则无泄漏;动作退化不会增加泄漏,与预测竞争理论相反。诊断建议:将目标从动态模型中移除(归于规划器成本),仅监督‘读取’路径,即可恢复真正的、不受指令影响的语义接地(0.88,有无目标结果一致)。该检测与修复方法适用于所有指令中包含评分项的目标条件模型。
原文摘要 · Abstract (English)
Compact world models that condition on a language goal promise to ground relations such as ``put the red block left of the blue block'' using a sparse set of explicit \emph{reference anchors}. We ask when such references actually ground a relation, and identify a trap: a goal-conditioned predictor reaches a striking $0.90$ relation-readout accuracy, yet this is \emph{instruction transcription}, not perception. Withholding the goal collapses it to chance ($0.90\!\to\!0.27$, three seeds) and a counterfactual instruction makes the predicted anchors follow the \emph{false} instruction $94.5\%$ of the time (true scene $2.3\%$; $N{=}256$). Tested across three settings and a within-task ablation, our central claim characterizes the confound: \textbf{instruction leakage occurs when the scored quantity is transcribable from the instruction (when the instruction names the answer) and is essentially independent of how predictive the non-instruction inputs are.} Our tabletop and the external BabyAI benchmark leak, whereas a Language-Table forward-dynamics world model whose instruction names \emph{referents} does not, until the instruction is augmented to name the direction; and degrading the action never increases leakage, the opposite of what predictor-competition predicts. The diagnosis prescribes the fix: keep the goal out of the dynamics (it belongs to the planner's cost) and supervise the \emph{read} path, recovering genuine, instruction-independent grounding ($0.88$, identical with and without the goal). The detection protocol and remedy apply to any goal-conditioned world model whose instruction names the scored quantity.
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